The hard core concentrates the force of a strike into a hard blow. It looks good on your set of keys since it has the nice polished finish. You can impress and show off, and of coarse it will intimidate potential threats. Fits finger holes sizes of any size, upto size 16-20. The key chain is nicely finished too. Overall Length: 2.75 Inches. Ring Size: 16+ Max. Construction: High-craft Aluminum, Two Hole. Finish: Electroplated, Polished Silver. Includes: Key Chain.